Long gone are the days when LEDs were of interest only to scientists and manufacturers of electronic equipment, who used them as luminous indicators of inclusion in the network. Now each of us meets with LEDs several times a day, although most often we don’t even know about it. Unusual lighting fixtures are fraught with a lot of possibilities. Where and for what purpose are they used in an apartment and a cottage?
Not passed even 130years since the invention of the first incandescent lamp, how mankind discovered a cheaper and more efficient lighting device– Light-emitting diode. Designers were among the first to appreciate its unique capabilities, using LEDs to illuminate interiors, building facades, fountains, pools and other objects.
What is an LED
Light-emitting diode– this is a semiconductor device, the action of which is based on the phenomenon of photon emission that occurs during the recombination of carriers of opposite charges in the contact area of semiconductor materials with different types of conductivity (the so-called district-transition).
The phenomenon of luminescence (the release of photons during Having recently appeared on the free market, LEDs have boldly invaded the world of artificial lighting, pushing out incandescent lamps, and even neon, almighty in the field of advertising, has done the aforementioned. pn-junction) accompanied the operation of the very first semiconductor diode, designed to pass current in one direction, and used as a rectifier. But it hindered rather than helped him perform his main functions. Well, as you know, with what interferes with work, we must fight in all possible ways. Andfought. Approximately to the middle 50sXXin. But by the end of this decade, the situation had changed, and work began to increase the brightness of the glow. Andearly 60sgg. the first diodes appeared, acting as a light source,– LEDs. They glowed red, very weakly, but nevertheless, they quickly found themselves used as turn-on indicators in a variety of devices, replacing mini-incandescent lamps. But things did not go beyond this for a long time.
FROMThe dead center process shifted in the early 90s when the first blue LED was created. True, to see its glow, it was necessary to use a powerful magnifying glass. BUTit cost so much! .. But it glowed. Then, according to experts, there was a revolution, which was made by the Japanese professor S.Nakamura by creating a bright blue LED. Further events unfolded like in a fast motion movie: green LEDs appeared, followed by yellow ones and finally white ones. Almost simultaneously with the development, preparations were made for their industrial production. Andfive-seven years ago they were first used in the creation of outdoor advertising. ATin the last year and a half, LEDs have become a mass product manufactured by manufacturers in Europe, Southeast Asia, the USA and Russia.
How it works
The basis of the LED (Light Emitting Diode, or LED) is an artificial semiconductor crystal with a size of 0.30.3mm, which implements the above pn-transition. The color of the glow depends on the material of the crystal. So, red and yellow LEDs, as a rule, are made on the basis of gallium arsenide, green and blue– based on gallium nitride. Glow enhancement is achieved in different ways. ATin some cases, special additives and additives are introduced into the composition of the crystal, in others– multilayer structures are used, which makes it possible to implement several crystals at once district-transitions, thereby increasing the brightness of its glow.
The crystal is “planted” in a polished metal cup (copper or aluminum), which is a reflector and a “cathode”(-). Tothe crystal itself is “welded” with a gold thread – “anode”(+). Then the entire structure is filled with a transparent compound, which is given a certain shape (let’s call it a flask). The angle of radiation of light emitted by the crystal depends on it. If the top of the bulb is flat, the light comes out in a wide beam (the angle is 120-130). If the top is convex, a lens is obtained that collects light into a narrower beam (angle 8-60). The smaller the radiation angle, the more intense the light flux gives the crystal. LEDs are produced in different colors: red, yellow, green, blue, blue-green and white, and white has recently come in several shades (cold, warm, “sunny” andt.d.). The cost of LEDs depends on the color and varies quite significantly. If we choose for example the simplest devices with a bulb diameter of 5mm, then the cheapest will be red (from $0.01), and the most expensive– green (from $0.15).
Naturally, the LED itself– plastic container with two thin legs-pinsIt’s not yet a full-fledged lighting fixture. To create such a device, it is necessary to ensure the stable operation of the diode. BUTto do this, it must be integrated into the appropriate wiring diagram. The fact is that, unlike an incandescent lamp, an LED needs LED modules used for local illumination and illumination of letters not only in a certain voltage, but also in the current flowing through it. That is, for the normal functioning of the device, it is not enough to apply voltage to the contacts so that the electrons begin to overcome the same pn-transition, while emitting photons (for example, it takes 2B, for blue and green– 3-4AT). It is also necessary to provide a certain current strength (for different diodes, its value ranges from 20 to 150mA), otherwise the LED will burn out quickly. Why? Action features pn-transitions are such that the voltage change is only 0.1B causes an increase in the current passing through the diode by several times. Andthis means that in order for the device to work normally, it is necessary to use a current stabilizer or at least a simple resistor circuit that limits the current.
So that the consumer does not do all this on his own, the LEDs are pre-installed on a printed circuit board with the desired electronic circuit. ATthe result is not just an LED, but an LED module– in terms of square, rectangular or rounded, equipped with its own contacts. This is the simplest lighting device that can be found on sale.
Modules with only limiting resistors are the cheapest ($0.5-2), but they require a power source that stably gives, for example, 12Q. If the circuit is a so-called electronic current regulator, the modules will cost more ($1-5). But, firstly, they will allow you to use a power source with a voltage of 10-90B, secondly, they will not suffer, even if you confuse “plus” with “minus” when connecting,– the circuit has a diode bridge (as experts joke, a “foolproof” circuit).
Relative market novelty– the so-called RGB-modules. They are assembled either on the basis of three diodes– red (Red), green (Green) and blue (Blue), hence the name,– either on the basis of three-color diodes, inside each of which crystals of three colors are hidden. The latest devices are somewhat more expensive (from $1) and managed Spotlights based on RGB LEDs, controlled by a special controller with a special controller. But thanks to the mixing of these colors in different proportions, they are able to glow with almost all shades of the rainbow spectrum.
FROMusing single modules, you can create, for example, luminous letters for congratulatory inscriptions, ornaments andt.n. But it must be said that this path is rarely followed. The so-called LED rulers are used much more often (there can be 4-24 light sources in them), equipped with a common contact group. Toall that remains is to connect the power supply (individual LEDs in the circuit are switched on in series, and as a result a higher total voltage is required– 12AT). Such a system can be made up of LEDs of the same or different colors, which allows using a single module to obtain the widest range of light colors (the module is controlled by a special controller).
There are rulers both without protection (a long printed circuit board with openly mounted diodes), and in a special case. When using the former, you will have to take care of their safety yourself (for example, you can hide the device under frosted plexiglass). On the other hand, they are flexible (the board is thin and bends easily), which makes it possible to “flow around” complex geometric surfaces (columns andt.P.). In the second case, the system is reliably protected from mechanical damage (for example, the American company SUPER VISION INTERNATIONAL offers devices that can be safely mounted in the risers of stairs). In addition, such models can be protected from moisture (IP65), which allows them to be used for garden and architectural lighting. It is not for nothing that PHILIPS (Netherlands) calls its products LEDline2 only spotlights. It is clear that the price of the rulers depends on the number of LEDs and their color ($8-25), as well as the presence of the hull and the degree of its protection (up to$1600). By the way, from such systems, as well as from modules, you can collect a variety of geometric shapes and patterns.
Next in difficulty– assemblies in the form of halogen (MP11-MP16), as well as conventional incandescent lamps (with a standard baseE27). ATanalogues of halogens from 19 to 33 LEDs (price– $12-30), in “incandescent lamps”– 32-132 LEDs (price– $12-150). Andboth have a built-in current stabilization system. ATIn general, take and install a new, LED lamp in place of the old lamp. True, it will not give as much light as the old one.– LED lamp with a power of 1-1.5W can be equated to an incandescent lamp with a power of 10-20W (however, LED lamps with higher light output have already appeared).
Ceiling lamp Origami (PHILIPS) Let’s start with the fact that LEDs have become widely used as a backlight in household appliances, such as refrigerators. On the basis of LEDs and LED assemblies, manufacturers produce a wide range of finished products. For example, PHILIPS offers Origami RGB recessed ceiling lights (from 200), spotlights for architectural lighting LEDflood (from 200), street lights on Equinox pole (from 600), floor or wall recessed LEDuplight model. ATproduct range of SUPER VISION INTERNATIONAL– a large selection of spotlights for both architectural lighting (SaVi Flood) and underwater (SaVi Spot). But one should not think that only foreign manufacturers are present on the market. So, a fairly wide range of projectors for architectural (Smart-RGB and Moscow series) and underwater (Eagle series) lighting, sets for creating a “starry sky” and much more are offered, for example, by the Svetovod LABORATORY. By the way, its protected (IP68) underwater floodlights may well be used in the garden.
(DECO NEON) with a spiral arrangement of LEDsHowever, the market offers are not limited to the listed devices. ATthere are now a huge number of flashlights on sale, from pocket to head ($1.5-100), Christmas (and not only) garlands, garden lamps that do not require an electrical connection (having a built-in solar battery, they are charged from the sun during the day), floating lanterns-balls for the pool (they are also charged from the sun) and festive winking at customers from almost every showcase of duralight– transparent “tubes”, inside which the same diodes glow ($3-15 for 1m length). All these products come to us from China and Southeast Asia. Speaking about Chinese products, we should note that among them there are also high-quality devices (they are produced by NEON KING, G-NOR, SANLIGHT, NEON-NEON, DECO NEON, GENIOR NEON KING), provided with at least a one-year warranty, and not very quality (sellers try not to even mention the names of their small producers).
By the way, about duralight. It is used not only for shop windows. FROMwith it, you can decorate the facade of the house for the holiday, creating a drawing on it, or simply highlight the contours or individual elements of the building. I don’t want to draw my own– buy a ready-made decorative composition. A wide variety of them is offered, for example, by the domestic company ITOG (price– from $9 to $400).
LEDs and illumination
LED diameter 5mm gives 1-5lumens of light.
For comparison: an incandescent lamp with a power of 100Tueis about 1000lumens, that is, to replace one such lamp, it is necessary to assemble about 500 LEDs into one design. But, unfortunately, it is not quite right to compare LEDs with conventional lamps in this way: the lamp gives diffused light, the LED– directed.
Different designs of LEDs are compared with each other by the strength of the light emitted by them, measured in candela. But in such a comparison, it is important to take into account the opening angle of the light beam emitted by the diode. For example, if we take two structures with the same radiation angle of 30, but having different luminous intensity, for example, 20 and 30 candela, then the second diode will be 1.5 times more powerful than the first. Well, if with a device of 20 candela and an angle of 30 compare a source of 30 candela with an angle of 60, it turns out that they create approximately the same luminous flux. ToWhy all these difficulties?
There are lighting standards. To work at a desk, illumination is required at least 300lux (for comparison: an incandescent lamp in 100W lighting 10m2 area, provides about 100lux). They measure the illumination in lux, and for this they use devices that are called– luxometers. No one measures anything in candela or lumens.
Andif you decide, for example, to illuminate your desktop with an LED table lamp, then, having heard that the proposed device gives 100candel, do not rush to buy it. It may very well be that these same 100candela are provided at an angle of radiation of 1-5 and the lamp will give normal illumination only on a small patch.
Candelais a unit of luminous intensity. oneThe candela is equal to the intensity of light emitted in a given direction by a section of a certain size of a reference light source.
Suite– unit of illumination. oneluxuryis the illumination created by the luminous flux 1lm, evenly distributed over a surface area of 1m2.
Lumen– unit of luminous flux. onelumen– the luminous flux emitted by a point source with a light intensity of 1 candela in a solid angle of 1steradian.
Points for and against”
Battery at 55BUTh provides up to 12days of operation of a floodlight with a capacity of 4.5Like all devices, LEDs have pros and cons. Toundoubted advantages include the fact that the conversion of electricity into light occurs with virtually no loss and with minimal energy consumption (recall: a diode needs a voltage of the order of 2V and current 20mA). This distinguishes such devices from both fluorescent lamps and incandescent lamps. Moreover, light emission is observed in a rather narrow part of the spectrum (light is close to monochromatic), which is especially appreciated by designers. BUTmain– the LED practically does not heat up (with the exception of powerful models of the latest generation, but even those are heated by an order of magnitude less than incandescent lamps), and its service life reaches 100thousandh. That is, almost 100 times more than an incandescent lamp, and five to ten times more than a fluorescent lamp. Tothis should be added high mechanical strength and exceptional reliability. AndFinally, given that the LED– the device is low-voltage, therefore, safe, we get an almost ideal light source!
Minuses two, but quite significant. First, as already mentioned, diodes do not give much light. Secondly, they are quite expensive. Today, the price of a lighting device assembled on LEDs is 10-50 times higher than that made with the usual incandescent lamps (naturally, with the same luminous flux created by both devices). True, experts say that in the next two or three years, prices will fall by about ten times.– apparently, then the “revolution” in lighting technology promised by experts will begin.
Light Tile (VILLEROYBOCH) equipped with LED lamps with a continuous operation resource of 100thousandhours At least 10years they will not require maintenanceTheoretically, the LED can work without interruption from 10 to 100thousandh (the first term is called by Chinese manufacturers, the second– European and American). Considering that it will turn on only in the evening and occasionally at night, we can assume that it will have 40-50 hours of lightyears. But this is theoretical. In practice, it should be taken into account that the design uses not only the LED itself, but also many auxiliary elements that have their own weak points: microcircuits with poor-quality soldering and oxidizing tracks, cases into which water seeps, andt.e. BAs a result, for example, products from China can be guaranteed for five years of operation.
FROMby Western manufacturers, the picture is fundamentally different– they give a guarantee not for LEDs, but for the entire product. AndThis means it will last much longer. True, and will cost two to three times more expensive than Chinese. What to do– you have to pay for quality.
What ensures such quality? Each firm has its own secret, and they disclose it with great reluctance. For example, one of the Dutch companies carries out the so-called annealing of LEDs: they are kept in an oven at a temperature of 60For about three days. After that, the diode is more stable in operation and provides a stable glow spectrum. True, the line of such devices is worth 85.
Now about what happens at the end of the warranty period. No, no, the diode will not “die” like an ordinary incandescent lamp. During this time, its brightness level will drop by no more than 50% (so-called crystal degradation will occur), but it will continue to work. ATdepending on the quality of manufacture, the crystals degrade in different ways: some gradually lose 3-5% of their brightness per year, others do it sharply, as soon as the appointed time approaches. But inevitably both those and others fade.
Note that the rate of degradation is greatly influenced by the temperature conditions of operation (the standards are indicated in the instrument’s passport and usually range from -40 to +40FROM). The lower the temperature, the longer the life of the LED. For example, somewhere in the north (at -20…-40C) it will be able to work almost forever (at this temperature, the crystal practically does not degrade). BUTNow, if you install it on a chimney, where the temperature is constantly high (60-80C), then he will live for about a year. ATsauna, where the temperature reaches 120C, it only lasts a few days. AndComplaining about poor quality product is useless.– the manufacturer can easily determine from the state of the crystal that the operating conditions are violated.
Where to use LEDs
Ceiling-mounted LED luminaires are designed to replace similar halogen ones. LEDs are used in almost all areas of lighting technology, with the exception of residential lighting. Although the idea of direct replacement of incandescent lamps with LED ones has not been perceived as fantastic for a long time.
Nevertheless, at home they can be used right now. For example, for emergency lighting. Since LEDs consume very little electricity, the capacity of a typical car battery (55BUTh), used as a backup power source, is enough to operate the emergency lighting system of a small country house (15-18 lamps) for a week. They are also indispensable for highlighting interiors, architectural details of buildings and landscapes. ATdwelling can be used to create:
emergency or night lighting;
luminous signs and patterns on doors, walls or ceilings, as well as “starry sky” systems;
light and color zoning of space;
furniture lighting, which allows you to give the usual interior items new bright images;
illumination of the collection stored on the racks.
ATthe last two cases, their use seems to be especially relevant. Small unbreakable LED modules can be integrated not only into newly manufactured furniture, but also into long-used furniture. Do you want to organize, for example, the backlight of a home bar counter?– no problem! Fasten (using self-tapping screws, glue and other methods) under the tabletop the required number of small rulers-modules of the desired colors, placed in a protective case,– and all. Unless the thin wires stretching to the LEDs need to be protected with a miniature cable channel.
For lighting collections, LEDs are generally indispensable. Firstly, they allow you to create an individual lighting option for each object (and they themselves are almost invisible). Secondly, they do not heat the illuminated “rarity”, no matter how close they are to it.
“ART-PHOTONICS” Now about architectural lighting. Of course, LED modules are not yet able to emit a luminous flux that would illuminate, like a spotlight, the entire facade at once. But they quite allow emphasizing individual architectural details and elements of this facade. So, with the help of LED rulers, you can flood them with light or highlight individual surfaces, Sealed luminous ball with a built-in solar battery, battery and automatic backlight switch will decorate both the pool and the alpine slide to create light cornices andt.e. At the same time, the backlight can be both white and colored, and even changing, for example, depending on the weather conditions and the temperature on the street (the famous Italian designer Carlo Pasolini tried to solve this problem in his time, which he succeeded with great difficulty). BUTyou can change the color of the facade as you wish. Using LED modules in tubular housings, you can create almost any pattern on the facade. Individual details of the building are also emphasized by LED spotlights. The only thing to consider when installing LED lamps,– that their cold light is not able to melt the snow.BUTtherefore, it is better to arrange them so that the luminous surface is facing down.
Andfinally, about the illumination of the pond and garden. When immersed in water, rich color LEDs “TOG” will allow you to achieve simply fantastic effects, while ensuring absolute electrical safety (IP68). In addition, your favorite pond or pool can be “populated” with floating luminous objects (for example, balls) that do not require power supply.
When designing a landscape, LEDs can be built into paths (including driveways), lawns, used to illuminate bushes and elements of garden architecture, as well as to indicate the dimensions of open entrance gates and garages. But it’s summer. BUTin winter, covered with snow, the entire named “exclusive”, unfortunately, will not be visible. But in winter, LEDs are successfully used to decorate trees, as well as to illuminate ice sculptures and the same frozen pond. And they don’t just illuminate them, but illuminate them from the inside.– from under the ice!
Where else is it beneficial to use LEDs? First of all, where it is impossible or too expensive to maintain lighting devices (hard-to-reach lighting of stairs, wall lighting hidden under protective glass behind the kitchen worktop, lamps built into the outer walls of buildings andt.P.). BUTeven where you need to drastically save electricity (for example, if only 3kW of electric power, and I really want to highlight its facade and the surrounding landscape) or high vandal resistance is important (luminaires in a special design in entrances, on elevator platforms, above the entrance gate). However, not everything can be listed.
The editors would like to thank PHILIPS, ART-PHOTONICS, ITOG, LABORATORY SVETOVOD, POLITEKS for their help in preparing the material.